Detecting consistency between radiation field and light field

Abstract

Methods and devices for detecting consistency between an invisible radiation field and a visible light field are provided. In an example, the method includes: an invisible radiation field is obtained by controlling a size of an opening of a beam limiting device; a first projection image is captured by an Electron Portal Imaging Device (EPID) as a distribution map of the invisible radiation field; a visible light field is obtained by turning on a light field lamp without changing the size of the opening of the beam limiting device; a phantom is positioned at each of vertices of the visible light field; a second projection image is captured by the EPID as a vertex distribution map of the visible light field; and deviation information between the invisible radiation field and the visible light field is determined according to the distribution map of the invisible radiation field and the vertex distribution map of the visible light field.

What is claimed is: 
     
       1. A method of detecting consistency between an invisible radiation field and a visible light field, comprising:
 generating an invisible radiation field by controlling a size of an opening of a beam limiting device; 
 capturing a first projection image with an Electron Portal Imaging Device (EPID) as a distribution map of the invisible radiation field; 
 generating a visible light field by turning on a light field lamp without changing the size of the opening of the beam limiting device; 
 positioning a phantom at each of vertices of the visible light field, wherein the phantom comprises:
 a base, 
 two cross engraved lines which are perpendicular with each other and disposed on a surface of the base, 
 a marker positioned at a point of intersection between the two cross engraved lines, 
 wherein attenuation of an X-ray beam by the base is less than attenuation of the X-ray beam by the marker; 
 
 capturing a second projection image by the EPID to generate a vertex distribution map of the visible light field, wherein the vertex distribution map comprises a projection of respective vertices of the visible light field; and 
 determining deviation information between the invisible radiation field and the visible light field based on the distribution map of the invisible radiation field and the vertex distribution map of the visible light field. 
 
     
     
       2. The method of  claim 1 , wherein the base comprises acrylic. 
     
     
       3. The method of  claim 1 , wherein:
 the marker comprises a metal sphere; and 
 a center of the marker is located substantially at the point of intersection between the two cross engraved lines. 
 
     
     
       4. The method of  claim 1 , wherein capturing the second projection image by the EPID comprises:
 enlarging the size of the opening of the beam limiting device such that each of the phantoms is within the visible light field; and 
 capturing the second projection image by the EPID. 
 
     
     
       5. The method of  claim 1 , wherein positioning the phantom at the vertex of the visible light field comprising:
 adjusting the two cross engraved lines of the phantom to substantially coincide with two sides of the visible light field intersecting at the vertex. 
 
     
     
       6. The method of  claim 1 , wherein determining the deviation information between the invisible radiation field and the visible light field according to the distribution map of the invisible radiation field and the vertex distribution map of the visible light field comprises:
 determining sides of the visible light field according to the projection of the respective vertices in the vertex distribution map of the visible light field, wherein the sides of the visible light field are taken as second sides; 
 determining side pairs according to first sides of the invisible radiation field and the second sides of the visible light field; 
 calculating a distance between two sides of each of the side pairs, wherein the deviation information comprises the distance between the two sides of the side pair. 
 
     
     
       7. The method of  claim 6 , wherein determining the side pairs according to the first sides of the invisible radiation field and the second sides of the visible light field comprises:
 generating a first linear equation for each of the first sides based on the distribution map of the invisible radiation field; and 
 generating a second linear equation for each of the second sides based on the projection of the respective vertices in the vertex distribution map of the visible light field, 
 wherein each of the side pairs comprises one of the first sides and one of the second sides, 
 wherein a slope difference between the first linear equation for the first side in the side pair and the second linear equation for the second side in the side pair is less than or equal to a first threshold, and 
 wherein an intercept difference between the first linear equation for the first side in the side pair and the second linear equation for the second side in the side pair is less than or equal to a second threshold. 
 
     
     
       8. The method of  claim 1 , wherein determining the deviation information between the invisible radiation field and the visible light field according to the distribution map of the invisible radiation field and the vertex distribution map of the light field comprises:
 determining each of first vertex coordinates of the invisible radiation field based on the distribution map of the invisible radiation field; 
 determining vertex pairs according to the projection of the respective vertices in the vertex distribution map of the visible light field and each of the first vertex coordinates; and 
 calculating a distance between two vertices of each of the vertex pairs, wherein the deviation information comprises the distance between two vertices of each of the vertex pairs. 
 
     
     
       9. The method of  claim 8 , wherein determining vertex pairs according to the projection of the respective vertices in the vertex distribution map of the visible light field and each of the first vertex coordinates comprises:
 determining each of second vertex coordinates of the visible light field based on the projection of the respective vertices in the vertex distribution map of the visible light field; 
 for each of the second vertex coordinates, finding one of the first vertex coordinates which is closest to the second vertex coordinate; and 
 determining a vertex pair which comprises the second vertex coordinate and the one of the first vertex coordinates closest to the second vertex coordinate. 
 
     
     
       10. A device for detecting consistency between an invisible radiation field and a visible light field, comprising:
 a processor; and 
 a non-transitory machine readable storage medium storing instructions, which, when executed cause the processor to perform a method, comprising:
 generating an invisible radiation field by controlling a size of an opening of a beam limiting device; 
 capturing a first projection image with an Electron Portal Imaging Device (EPID) as a distribution map of the invisible radiation field; 
 generating a visible light field by turning on a light field lamp without changing the size of the opening of the beam limiting device; 
 positioning a phantom at each of vertices of the visible light field, wherein the phantom comprises:
 a base, 
 two cross engraved lines which are perpendicular with each other and disposed on a surface of the base, 
 a marker positioned at a point of intersection between the two cross engraved lines, 
 wherein attenuation of an X-ray beam by the base is less than attenuation of the X-ray beam by the marker; 
 
 capturing a second projection image by the EPID to generate a vertex distribution map of the visible light field, wherein the vertex distribution map comprises a projection of respective vertices of the visible light field; and 
 determining deviation information between the invisible radiation field and the visible light field based on the distribution map of the invisible radiation field and the vertex distribution map of the visible light field. 
 
 
     
     
       11. The device of  claim 10 , wherein the base comprises acrylic. 
     
     
       12. The device of  claim 10 , wherein:
 the marker comprises a metal sphere; and 
 a center of the marker is located substantially at the point of intersection between the two cross engraved lines. 
 
     
     
       13. The device of  claim 10 , wherein when capturing the second projection image by the EPID, the processor is caused by the machine executable instructions to:
 enlarge the size of the opening of the beam limiting device such that each of the phantoms is within the visible light field; and 
 capture the second projection image by the EPID. 
 
     
     
       14. The device of  claim 10 , wherein when determining the deviation information between the invisible radiation field and the visible light field according to the distribution map of the invisible radiation field and the vertex distribution map of the visible light field, the processor is caused by the machine executable instructions to:
 determine sides of the visible light field according to the projection of the respective vertices in the vertex distribution map of the visible light field, wherein the sides of the visible light field are taken as second sides; 
 determine side pairs according to first sides of the invisible radiation field and the second sides of the visible light field; 
 calculate a distance between two sides of each of the side pairs, wherein the deviation information comprises the distance between the two sides of the side pair. 
 
     
     
       15. The device of  claim 14 , wherein when determining the side pairs according to the first sides of the invisible radiation field and the second sides of the visible light field, the processor is caused by the machine executable instructions to:
 generate a first linear equation for each of the first sides based on the distribution map of the invisible radiation field; 
 generate a second linear equation for each of the second sides based on the projection of the respective vertices in the vertex distribution map of the visible light field; and 
 wherein each of the side pairs comprises one of the first sides and one of the second sides, 
 wherein a slope difference between the first linear equation for the first side in the side pair and the second linear equation for the second side in the side pair is less than or equal to a first threshold, and 
 wherein an intercept difference between the first linear equation for the first side in the side pair and the second linear equation for the second side in the side pair is less than or equal to a second threshold. 
 
     
     
       16. The device of  claim 10 , wherein when determining the deviation information between the invisible radiation field and the visible light field according to the distribution map of the invisible radiation field and the vertex distribution map of the visible light field, the processor is caused by the machine executable instructions to:
 determine each of first vertex coordinates of the invisible radiation field based on the distribution map of the invisible radiation field; 
 determine vertex pairs according to the projection of the respective vertices in the vertex distribution map of the visible light field and each of the first vertex coordinates; and 
 calculate a distance between two vertices of each of the vertex pairs, wherein the deviation information comprises the distance between two vertices of each of the vertex pairs. 
 
     
     
       17. The device of  claim 16 , wherein when determining vertex pairs according to the projection of the respective vertices in the vertex distribution map of the visible light field and each of the first vertex coordinates, the processor is caused by the machine executable instructions to:
 determine each of second vertex coordinates of the visible light field based on the projection of the respective vertices in the vertex distribution map of the visible light field; 
 for each of the second vertex coordinates, find one of the first vertex coordinates which is closest to the second vertex coordinate; and 
 determine a vertex pair which comprises the second vertex coordinate and the one of the first vertex coordinates closest to the second vertex coordinate.